1. Field of the Invention
This invention relates to a guide device preferred for application to a delivery device for delivering sheets, which have been transported after being printed in a sheet-fed press, by transferring the sheets to a plurality of piling devices arranged in parallel in a sheet transport direction.
2. Description of the Related Art
In a sheet-fed press, a sheet printed by a printing apparatus is transferred from a gripper of a printing cylinder to a delivery gripper of a delivery chain, and is transported as the delivery chain runs. Then, the sheet is released from the delivery gripper above a pile board, and dropped onto the pile board for piling.
A conventional delivery device will be described based on FIGS. 8 and 9 (see Japanese Utility Model Registration No. 2588807). FIG. 8 is a schematic configuration drawing of a conventional delivery device, and FIG. 9 is a plan view of a sheet guide device.
As shown in FIG. 8, a delivery cylinder 3 is provided in opposed relationship with an impression cylinder 2 of a printing apparatus 1. A delivery chain 6 is looped between the delivery cylinder 3 and a sprocket 5 located in a rear portion of a delivery device 4. Many delivery grippers 7 are provided in the delivery chain 6, and printed sheets 8 are transferred from the delivery cylinder 3 to the delivery grippers 7, whereafter the printed sheets 8 are transported, while gripped by the delivery grippers 7, as the delivery chain 6 runs.
In the delivery device 4, two piling devices 9 and 10 (first pile 9, second pile 10) are installed in parallel in the transport direction of the sheet 8. The sheet 8 is released from the delivery gripper 7 above the first pile 9 or the second pile 10, and dropped onto the first pile 9 or the second pile 10 for piling.
A sheet lay 11 is provided on a downstream side of each of the first pile 9 and the second pile 10 in the direction of sheet transport. The front end of the sheet 8, released from the delivery gripper 7, contacts the sheet lay 11 to become positioned in the direction of sheet transport, and the sheet 8 comes to a stop. A suction wheel 12 is provided on an upstream side of each of the first pile 9 and the second pile 10 in the direction of sheet transport to be movable in the direction of sheet transport. The rear end of the sheet 8, released from the delivery gripper 7, is sucked by the suction wheel 12. The sheet 8 is reduced in speed under this sucking action, so that shock upon its contact with the sheet lay 11 is absorbed.
A sheet guide device 13 is provided beside the sheet lay 11 of the first pile 9, and the sheet guide device 13 is adapted to cover the upper surface of the first pile 9 from a downstream side toward an upstream side in the direction of sheet transport.
The sheet guide device 13 will be described based on FIG. 9. A sheet lay shaft 15 is supported rotatably between right and left frames 14 of the delivery device 4. A plurality of (five in the illustrated embodiment) the aforementioned sheet lays 11 are mounted on the sheet lay shaft 15, and the five sheet lays 11 are simultaneously erected by rotation of the sheet lay shaft 15.
Right and left paired guides 16 extending in the direction of sheet transport are mounted on the frames 14, and a base 17 extending parallel to the sheet lay shaft 15 is supported between these guides 16 to be movable in the direction of sheet transport. Sheet bearers 19 with rollers are mounted on the base 17 via a plurality of (nine in the illustrated embodiment) support plates 18, and the sheet bearers 19 extend upstream from the base 17 in the direction of sheet transport.
A stationary base 20 is installed, parallel to the above-mentioned base 17, between end portions of the guides 16 on a downstream side in the direction of sheet transport. A moving mechanism 24 of a parallel ruler type, which consists of an X-link 21, an air cylinder 22, and slots 23a to 23d, is interposed between the stationary base 20 and the base 17. Thus, the base 17 makes a reciprocating motion in the direction of sheet transport under the expanding and contracting action of the air cylinder 22, whereby the sheet bearers 19 become movable between a guide position (the state of solid lines in FIG. 9), where the sheet bearers 19 cover the upper surface of the first pile 9 on the downstream side in the direction of sheet transport, and a retreat position (see double-dotted chain lines in FIG. 9), where the sheet bearers 19 expose this upper surface.
According to the delivery device 4 with the above features, the sheets 8, which have been printed by the printing apparatus 1 and transported to the delivery device 4 by the delivery chain 6, are delivered to the first pile 9 and the second pile 10 switched alternately. Hence, the printing press can be continuously operated without being shut down, thereby achieving improved productivity. Since the first pile 9 and the second pile 10 are provided, moreover, defective sheets can be detected by a defective sheet detector (not shown), and only the defective sheets can be delivered to the second pile 10. Alternatively, only arbitrary sheets 8, which are to be inspected, for example, by inspection of printing, can be with drawn to the second pile 10. Further alternatively, if one of the first pile 9 and the second pile 10 is full of the sheets 8, this full pile can be switched to the other pile, and the sheets 8 filling up the one pile can be discharged.
In the above-described delivery device 4 having the first pile 9 and the second pile 10 arranged side by side in the direction of transport of the sheet 8, when the sheet 8 is to be delivered to the second pile 10, the sheet 8 gripped by the delivery gripper 7 passes above the first pile 9, but a rear end portion of the sheet 8 is free and flutters or moves unstably. On this occasion, the sheet bearers 19 are moved to the guide position where the sheet bearers 19 cover the upper surface of a downstream side to an upstream side of the first pile 9 in the direction of sheet transport, whereby the fluttering or instability of the sheet can be prevented to minimize a decline in printing quality or the like.
With the foregoing conventional delivery device 4, however, when the sheet bearers 19 located at the retreat position (the position between the piles) are moved to the guide position, no guide member is present at the retreat position (the position between the piles). In addition, the distance between the piles, over which no guide member is existent, increases because the suction wheel 12 moves from the upstream side to the downstream side in the direction of sheet transport. This causes 8 occurs between the piles. In brief, the sheet bearers 19 alone are not enough to prevent the fluttering or instability of the sheet 8.
In guiding the sheet 8, moreover, if opposite end portions, in particular, of the sheet 8 in its width direction are not supported, these opposite end portions droop. However, the sheet bearers 19 of the sheet guide device 13 cannot be position-adjusted in the lateral direction (the direction perpendicular to the direction of sheet transport). Thus, in the case of a change in the sheet size (the size in the width direction), for example, there is the problem that the opposite end portions of the sheet cannot be guided unerringly.
In addition, since the sheet bearers 19 cannot be position-adjusted in the width direction of the sheet 8, a side jogger (not shown) interferes with the sheet bearer 19, in the case of a change in the sheet size (for example, a change from a large size to a small size in the width direction) . Thus, the sheet bearers 19 on the right-hand and left-hand sides need to be removed from the support plates 18. At this time, bolts are detached by use of a tool, thus requiring that the printing press be shut down, the sheets 8 be pulled out of the first pile 9 to secure a work space, and removal work be done. This results in a low work efficiency. In a printing machine equipped with an automated device, such as a sheet size preset device, the sheet size is changed with the touch of a button. With such a machine, if the above-mentioned work fails to be performed, a trouble occurs, such as an operational failure or a damage to a component.
Besides, when the aforementioned delivery device 4 is to be applied to a perfecting printing press or a printing press in which sheet is transported with its printed surface directed downward, printed areas of the back of the sheet 8 may contact the sheet bearer 19 or the like to stain the printed surface by rubbing. To prevent this event, the sheet bearer 19 should be moved to a position where the sheet bearers 19 guide the non-printed areas (the margins) of the sheet 8. However, the sheet bearers 19 cannot be position-adjusted in the width direction of the sheet 8, and thus cannot be moved to that position. Hence, the delivery device 4 cannot be applied to such a printing press.